A continuing demand exists for a simple, high efficiency, inexpensive power plant which can reliably provide electrical and mechanical power. A variety of medium size electrical or mechanical power plants could substantially benefit from a prime mover which provides a marked improvement in overall efficiency. Such medium size mechanical or electrical power plants--in the 10 to 100 megawatt range--are required in a wide range of industrial applications, including rail locomotives, marine power systems, aircraft engines, and stationary electric power generating units. Power plants in this general size range are also well suited to use in industrial cogeneration facilities. Such facilities are increasingly employed to service industrial thermal power needs while simultaneously generating electrical power.
Power plant designs which are now commonly found in co-generation applications include (a) gas turbines, driven by the combustion of natural gas, fuel oil, or other fuels, and capturing the thermal and kinetic energy from the combustion gases, (b) steam turbines, driven by the steam which is generated in boilers from the combustion of coal, fuel oil, natural gas, solid waste, or other fuels, and (c) large scale reciprocating engines, usually diesel cycle and typically fired with fuel oils.
Each of the aforementioned types of power plants are complex integrated systems. Such plants often include many subsystems and a large number of individual parts. The parts often must be manufactured to exacting dimensional and mechanical specifications. As a result, such power plants are relatively expensive to manufacture, to install, and to operate. Also, in the event of failure of a part or subsystem, the required repairs are often quite expensive. Frequently, repairs may require substantial disassembly of subsystems to gain access to individual parts, in order to repair or replace the faulty components and return the plant to an operational condition.
Of the currently available power plant technologies, diesel fueled reciprocating and advanced turbine engines have the highest efficiency levels. Base efficiencies are often in the range of 25% to 40%, based on net work produced when compared to the energy value of the fuel source. Unfortunately, at power output levels greater than approximately 1 megawatt, the size of the pistons and other engine components required by reciprocating engine systems become almost unmanageably large, and as a result, widespread commercial use of larger sized reciprocating engine systems has not been accomplished.
Gas turbines perform more reliably than reciprocating engines, and are therefore frequently employed in plants which have higher power output levels. However, because gas turbines are only moderately efficient in converting fuel to electrical energy, gas turbine powered plants are most effectively employed in co-generation systems where, as mentioned above, both electrical and thermal energy can be utilized. In that way, the moderate efficiency of a gas turbine can in part be counterbalanced by increasing the overall cycle efficiency.
Fossil fueled steam turbine electrical power generation systems are also of fairly low efficiency, often in the range of 30% to 40%. Such systems are commonly employed in both utility and industrial applications for base load electrical power generation. This is primarily due to the high reliability of such systems. However, like gas turbine equipment, steam turbine equipment is most advantageously employed in situations where both mechanical and thermal energy may be utilized, thus increasing overall cycle efficiency.
Because of their moderate efficiency in conversion of fuel input to electrical output, the most widely used types of power plants, namely gas turbines and combustion powered steam turbine systems, depend upon co-generation in industrial settings to achieve advantageous commercial electricity cost levels. Thus, it can be appreciated that it would be desirable to be able to generate electrical power at higher overall efficiency rates than is commonly achieved today, especially when compared to the currently utilized gas and steam turbine based power plants.